Heat pipe assembly for dissipating heat in a drain pump

ABSTRACT

A washing machine appliance is provided including a sump for collecting wash fluid and a pump assembly fluidly coupled to the sump for urging a flow of wash fluid. The pump assembly includes a pump housing, a pump impeller, and a drive motor for selectively rotating the pump impeller. A heat pipe assembly extends between the drive motor and the flow of wash fluid to transfer thermal energy generated by the motor to the wash fluid. For example, an evaporator section of the heat pipe may be in direct contact with the drive motor and a condenser section of the heat pipe may be positioned within pump housing.

FIELD OF THE INVENTION

The present subject matter relates generally to drain pump assembliesfor washing machine appliances, or more specifically, to heat pipeassemblies for use with drain pump assemblies

BACKGROUND OF THE INVENTION

Washing machine appliances generally include a tub for containing wateror wash fluid, e.g., water and detergent, bleach, and/or other washadditives. A basket is rotatably mounted within the tub and defines awash chamber for receipt of articles for washing. During normaloperation of such washing machine appliances, the wash fluid is directedinto the tub and onto articles within the wash chamber of the basket.The basket or an agitation element can rotate at various speeds toagitate articles within the wash chamber, to wring wash fluid fromarticles within the wash chamber, etc.

During a spin or drain cycle, a drain pump assembly may operate todischarge water from within sump. Such drain pumps typically include animpeller positioned within a pump housing and an electric drive motorfor rotating the impeller and discharging wash fluid. However, duringextended pumping action, the core of the electric drive motor can getvery warm and can make the pump weaker. For example, the pump's startingtorque reduces when the drive motor gets very warm. In extreme cases,the drive motor even can reach a thermal cut off point where the pumpassembly shuts down. Conventional washing machine drain pumps do nothave integrated cooling mechanisms that actively help in dissipatingheat generated in the motor core. Thus, heat generated by the winding inthe motor core normally dissipates slowly to the surrounding air.

Accordingly, a washing machine appliance having an improved drain pumpassembly would be desirable. More particularly, a drain pump assemblyincluding a heat pipe for dissipating heat and facilitating prolongedpumping operation would be particularly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

Advantages of the invention will be set forth in part in the followingdescription, or may be apparent from the description, or may be learnedthrough practice of the invention.

In accordance with one exemplary embodiment of the present disclosure, awashing machine appliance is provided including a sump for collectingwash fluid and a pump assembly in fluid communication with the sump forselectively urging a flow of wash fluid from the sump. A heat pipeassembly provides thermal communication between the pump assembly andthe flow of wash fluid for transferring thermal energy from the pumpassembly to the flow of wash fluid.

In accordance with another exemplary embodiment of the presentdisclosure, a washing machine appliance is provided including a sump forcollecting wash fluid. A pump housing is in fluid communication with thesump, a pump impeller rotatably is mounted within the pump housing, anda drive motor selectively rotates the pump impeller to urge a flow ofwash fluid within the pump housing. A heat pipe assembly includes anevaporator section and a condenser section, the heat pipe assemblyproviding thermal communication between the drive motor and the flow ofwash fluid.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures.

FIG. 1 provides a perspective view of an exemplary washing machineappliance according to an exemplary embodiment of the present subjectmatter.

FIG. 2 provides a side cross-sectional view of the exemplary washingmachine appliance of FIG. 1.

FIG. 3 provides a rear, perspective view of a drain pump assembly and awater level detection system according to an exemplary embodiment of thepresent subject matter.

FIG. 4 provides a side, perspective view of the exemplary drain pumpassembly of FIG. 3 according to an embodiment of the present subjectmatter.

FIG. 5 provides an exploded view of the exemplary drain pump assembly ofFIG. 4 according to an embodiment of the present subject matter.

FIG. 6 provides a side, schematic view of the exemplary drain pumpassembly of FIG. 3 including a heat pipe assembly according to oneembodiment of the present subject matter.

FIG. 7 provides a side, schematic view of the exemplary drain pumpassembly of FIG. 3 including a heat pipe assembly according to anotherembodiment of the present subject matter.

FIG. 8 provides a top, schematic view of the exemplary drain pumpassembly of FIG. 3 including a heat pipe assembly according to anotherembodiment of the present subject matter.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the terms “upstream” and “downstream” refer to therelative direction with respect to fluid flow in a fluid pathway. Forexample, “upstream” refers to the direction from which the fluid flows,and “downstream” refers to the direction to which the fluid flows.Furthermore, as used herein, terms of approximation, such as“approximately,” “substantially,” or “about,” refer to being within aten percent margin of error.

Referring now to the figures, FIG. 1 is a perspective view of anexemplary horizontal axis washing machine appliance 100 and FIG. 2 is aside cross-sectional view of washing machine appliance 100. Asillustrated, washing machine appliance 100 generally defines a verticaldirection V, a lateral direction L, and a transverse direction T, eachof which is mutually perpendicular, such that an orthogonal coordinatesystem is generally defined. Washing machine appliance 100 includes acabinet 102 that extends between a top 104 and a bottom 106 along thevertical direction V, between a left side 108 and a right side 110 alongthe lateral direction L, and between a front 112 and a rear 114 alongthe transverse direction T.

Referring to FIG. 2, a wash basket 120 is rotatably mounted withincabinet 102 such that it is rotatable about an axis of rotation A. Amotor 122, e.g., such as a pancake motor, is in mechanical communicationwith wash basket 120 to selectively rotate wash basket 120 (e.g., duringan agitation or a rinse cycle of washing machine appliance 100). Washbasket 120 is received within a wash tub 124 and defines a wash chamber126 that is configured for receipt of articles for washing. The wash tub124 holds wash and rinse fluids for agitation in wash basket 120. Asused herein, “wash fluid” may refer to water, detergent, fabricsoftener, bleach, or any other suitable wash additive or combinationthereof. Indeed, for simplicity of discussion, these terms may all beused interchangeably herein without limiting the present subject matterto any particular “wash fluid.”

Wash basket 120 may define one or more agitator features that extendinto wash chamber 126 to assist in agitation and cleaning articlesdisposed within wash chamber 126 during operation of washing machineappliance 100. For example, as illustrated in FIG. 2, a plurality ofribs 128 extends from basket 120 into wash chamber 126. In this manner,for example, ribs 128 may lift articles disposed in wash basket 120during rotation of wash basket 120.

Referring generally to FIGS. 1 and 2, cabinet 102 also includes a frontpanel 130 which defines an opening 132 that permits user access to washchamber 126 of wash basket 120. More specifically, washing machineappliance 100 includes a door 134 that is positioned over opening 132and is rotatably mounted to front panel 130. In this manner, door 134permits selective access to opening 132 by being movable between an openposition (not shown) facilitating access to a wash chamber 126 and aclosed position (FIG. 1) prohibiting access to wash chamber 126.

A window 136 in door 134 permits viewing of wash chamber 126 when door134 is in the closed position, e.g., during operation of washing machineappliance 100. Door 134 also includes a handle (not shown) that, e.g., auser may pull or push when opening and closing door 134. Further,although door 134 is illustrated as mounted to front panel 130, itshould be appreciated that door 134 may be mounted to another side ofcabinet 102 or any other suitable support according to alternativeembodiments.

Referring again to FIG. 2, wash basket 120 also defines a plurality ofperforations 140 in order to facilitate fluid communication between aninterior of basket 120 and wash tub 124. A sump 142 is defined by washtub 124 at a bottom of wash tub 124 along the vertical direction V.Thus, sump 142 is configured for receipt of and generally collects washfluid during operation of washing machine appliance 100. For example,during operation of washing machine appliance 100, wash fluid may beurged by gravity from basket 120 to sump 142 through plurality ofperforations 140.

A drain pump assembly 144 is located beneath wash tub 124 and is influid communication with sump 142 for periodically discharging soiledwash fluid from washing machine appliance 100. Drain pump assembly 144may generally include a drain pump 146 which is in fluid communicationwith sump 142 and with an external drain 148 through a drain hose 150.During a drain cycle, drain pump 146 urges a flow of wash fluid fromsump 142, through drain hose 150, and to external drain 148. Morespecifically, as described in detail below in reference to FIGS. 3through 9, drain pump 146 includes a motor which is energized during adrain cycle such that drain pump 146 draws wash fluid from sump 142 andurges it through drain hose 150 to external drain 148.

A spout 154 is configured for directing a flow of fluid into wash tub124. For example, spout 154 may be in fluid communication with a watersupply (not shown) in order to direct fluid (e.g., clean water) intowash tub 124. Spout 154 may also be in fluid communication with the sump142. For example, pump assembly 144 may direct wash fluid disposed insump 142 to spout 154 in order to circulate wash fluid in wash tub 124.

As illustrated in FIG. 2, a detergent dispenser 156 may be slidablymounted within front panel 130. Detergent dispenser 156 receives a washadditive (e.g., detergent, fabric softener, bleach, or any othersuitable liquid or powder) and directs the fluid additive to wash tub124 during operation of washing machine appliance 100. According to theillustrated embodiment, detergent dispenser 156 may also be fluidlycoupled to spout 154 to facilitate the complete and accurate dispensingof wash additive.

In addition, a water supply valve 158 may provide a flow of water from awater supply source (such as a municipal water supply) into detergentdispenser 156 and into wash tub 124. In this manner, water supply valve158 may generally be operable to supply water into detergent dispenser156 to generate a wash fluid, e.g., for use in a wash cycle, or a flowof fresh water, e.g., for a rinse cycle. It should be appreciated thatwater supply valve 158 may be positioned at any other suitable locationwithin cabinet 102.

A control panel 160 including a plurality of input selectors 162 iscoupled to front panel 130. Control panel 160 and input selectors 162collectively form a user interface input for operator selection ofmachine cycles and features. For example, in one embodiment, a display164 indicates selected features, a countdown timer, and/or other itemsof interest to machine users.

Operation of washing machine appliance 100 is controlled by a controlleror processing device 166 (FIG. 1) that is operatively coupled to controlpanel 160 for user manipulation to select washing machine cycles andfeatures. In response to user manipulation of control panel 160,controller 166 operates the various components of washing machineappliance 100 to execute selected machine cycles and features.

Controller 166 may include a memory and microprocessor, such as ageneral or special purpose microprocessor operable to executeprogramming instructions or micro-control code associated with acleaning cycle. The memory may represent random access memory such asDRAM, or read only memory such as ROM or FLASH. In one embodiment, theprocessor executes programming instructions stored in memory. The memorymay be a separate component from the processor or may be includedonboard within the processor. Alternatively, controller 166 may beconstructed without using a microprocessor, e.g., using a combination ofdiscrete analog and/or digital logic circuitry (such as switches,amplifiers, integrators, comparators, flip-flops, AND gates, and thelike) to perform control functionality instead of relying upon software.Control panel 160 and other components of washing machine appliance 100may be in communication with controller 166 via one or more signal linesor shared communication busses.

During operation of washing machine appliance 100, laundry items areloaded into wash basket 120 through opening 132, and washing operationis initiated through operator manipulation of input selectors 162. Washtub 124 is filled with water, detergent, and/or other fluid additives,e.g., via spout 154 and or detergent dispenser 156. One or more valves(e.g., water supply valve 158) can be controlled by washing machineappliance 100 to provide for filling wash basket 120 to the appropriatelevel for the amount of articles being washed and/or rinsed. By way ofexample for a wash mode, once wash basket 120 is properly filled withfluid, the contents of wash basket 120 can be agitated (e.g., with ribs128) for washing of laundry items in wash basket 120.

After the agitation phase of the wash cycle is completed, wash tub 124can be drained. Laundry articles can then be rinsed by again addingfluid to wash tub 124, depending on the particulars of the cleaningcycle selected by a user. Ribs 128 may again provide agitation withinwash basket 120. One or more spin cycles may also be used. Inparticular, a spin cycle may be applied after the wash cycle and/orafter the rinse cycle in order to wring wash fluid from the articlesbeing washed. During a final spin cycle, basket 120 is rotated atrelatively high speeds and drain pump assembly 144 may discharge washfluid from sump 142. After articles disposed in wash basket 120 arecleaned and/or washed, the user can remove the articles from wash basket120, e.g., by opening door 134 and reaching into wash basket 120 throughopening 132.

While described in the context of a specific embodiment of horizontalaxis washing machine appliance 100, using the teachings disclosed hereinit will be understood that horizontal axis washing machine appliance 100is provided by way of example only. Other washing machine applianceshaving different configurations, different appearances, and/or differentfeatures may also be utilized with the present subject matter as well,e.g., vertical axis washing machine appliances.

Referring now to FIG. 3, drain pump assembly 144 that may be used withinwashing machine appliance 100 will be described according to anexemplary embodiment. As shown, sump 142 defines a drain basin at alowest point of wash tub 124 for collecting wash fluid under the forceof gravity. Drain pump assembly 144 is positioned proximate bottom 106of cabinet and a sump hose 172 extends between sump 142 and an intake174 of drain pump 146. According to the illustrated embodiment, drainpump 146 is a centrifugal pump configured for urging wash fluid thatcollects in sump 142 and sump hose 172 through a pump discharge 176,through drain hose 150, and to external drain 148. However, it should beappreciated that the drain pump assembly 144 and the sump drainageconfiguration illustrated herein are only exemplary and not intended tolimit the scope of the present subject matter. For example, drain pump146 may have a different configuration or position, may be attacheddirectly to sump 142 bypassing the need for sump hose 172, may includeone or more filtering mechanisms, etc.

Referring now specifically to FIGS. 4 and 5, drain pump 146 generallyincludes a pump housing 200, a pump impeller 202 rotatably mountedwithin pump housing 200, and a drive motor 204 that is operably coupledwith pump impeller 202 for selectively rotating pump impeller 202 tourge a flow of wash fluid (e.g., as identified by arrows 206). Morespecifically, pump housing 200 may define pump intake 174 through whichwash fluid may be channeled from sump 142. In addition, pump housing 200may define a volute 210 within which pump impeller 202 is positioned forurging the flow of wash fluid 206 and a discharge conduit 212 that ispositioned downstream from volute 210 and is fluidly coupled to drainhose 150.

Drive motor 204 may generally be any suitable electric motor which isoperably coupled with pump impeller 202. For example, drive motor 204may be a brushless DC electric motor, e.g., a pancake motor, an ACmotor, an induction motor, a permanent magnet synchronous motor, or anyother suitable type of motor. As illustrated, drive motor 204 generallyincludes a stator 220 positioned within a motor housing (not shown) anda rotor 222 rotatably positioned within the stator 220.

Stator 220 may be mechanically coupled within the motor housing (e.g.,by one or more mechanical fasteners or through a compression fit) suchthat rotation relative to motor housing is prevented. By contrast, rotor222 is rotatably mounted using one or more bearings 224. When energizedwith the appropriate power, rotor 222 is caused to rotate while stator220 remains fixed. For example, according to an exemplary embodiment,stator 220 includes magnetic windings 226 wound around a lamination core228. Each magnetic winding 226 may be formed from insulated conductivewire. When assembled, the stator 220 may be circumferentially positionedabout rotor 222 to electromagnetically engage and drive rotation ofrotor 222.

According to the illustrated embodiment, pump housing 200 is positionedabove drive motor 204 along the vertical direction V. In addition, pumpimpeller 202 may be operably coupled with drive motor 204 in anysuitable manner. For example, pump impeller 202 may be mechanicallycoupled to rotor 222, e.g., by direct mounting to a rotor shaft.Alternatively, pump impeller 202 may be magnetically coupled to rotor222. Although an exemplary drive motor 204 is described herein, itshould be appreciated that according to alternative embodiments, anyother suitable drive motor may be used having any other type,configuration, or orientation.

Notably, drive motor 204 has a tendency to heat up during operation ofdrain pump assembly 144. In particular, if the drain cycle lasts longenough or the load on drive motor 204 is excessively large, drive motor204 may reach a thermal cut-off temperature at which point drain pumpassembly 144 shuts down altogether. Aspects of the present subjectmatter are directed to systems for regulating the temperature generatedby drive motor 204, thereby avoiding high temperatures which can resultoperational issues for drive motor 204.

Specifically, referring now to FIGS. 6 through 8, washing machineappliance 100 may further include a heat pipe assembly 240 for providingthermal communication between pump assembly 144 and the flow of washfluid 206 for transferring thermal energy from pump assembly 144 to theflow of wash fluid 206. More specifically, heat pipe assembly 240 isgenerally configured for cooling drive motor 204 of pump assembly 144 toavoid high temperature operation and permit drive motor 204 to operatefor longer or higher-load periods without reaching a thermal cut-offpoint or temperature. In general, heat pipe assembly 240 is a type ofheat exchanger used to transfer thermal energy through the evaporationand condensation of a working fluid, as described in more detail below

As shown, heat pipe assembly 240 includes one or more heat pipes 242which each include a sealed casing 244 containing a working fluid 246within casing 244. The casing 244 is preferably constructed of amaterial with a high thermal conductivity, such as a metal, such ascopper or aluminum. In some embodiments, the working fluid 246 may bewater. In other embodiments, suitable working fluids for the heat pipe242 include acetone, methanol, ethanol, or toluene. Any suitable fluidmay be used for working fluid 246, e.g., any fluid that is compatiblewith the material of the casing 244 and is suitable for the desiredoperating temperature range.

According to the illustrated embodiment, heat pipe 242 generally extendsbetween a condenser section 248 at one end of heat pipe 242 and anevaporator section 250 at an opposite end of heat pipe 242. The workingfluid 246 contained within the casing 244 of the heat pipe 242 absorbsthermal energy at the evaporator section 250, whereupon the workingfluid 246 travels in a gaseous state from the evaporator section 250 tothe condenser section 248. At the condenser section 248, the gaseousworking fluid 246 condenses to a liquid state and thereby releasesthermal energy. Notably, by positioning condenser section 248 with inthe flow of wash fluid 206, which is moving any time drive motor 204 isrunning and is cooler than working fluid 246, a high rate of thermaltransfer may be achieved.

According to an exemplary embodiment, heat pipe 242 may include aplurality of surface aberrations, protrusions, or fins 252 forincreasing the rate of thermal transfer. In this regard, fins 252 may beprovided on an external surface of the casing 244 at either or both ofthe condenser section 248 and the evaporator section 250. Fins 252 mayprovide an increased contact area between the heat pipe 242 and drivemotor 204 or the flow of wash fluid 206. Fins 252 are particularlyadvantageous at the condenser section 248 where they readily dischargeheat to the flow of wash fluid 206. According to alternativeembodiments, no fins 252 are used and casing 244 is simply a smooth heatexchange pipe.

In general, evaporator section 250 may be physically connected to drivemotor 204, may be positioned adjacent to drive motor 204, or mayotherwise be in thermal communication with drive motor 204. Thus, asdrive motor 204 heats up during operation, thermal energy from drivemotor 204 may transfer to working fluid 246, which evaporates andtravels through heat pipe 242 toward condenser section 248. Thermalenergy from the evaporated working fluid 246 is then transferred throughcasing 244 and fins 252 to the flow of wash fluid 206. As the workingfluid 246 cools, it will condense and flow in liquid form back to theevaporator section 250, e.g., by gravity and/or capillary flow.

According to exemplary embodiments, heat pipe 242 may further include aninternal wick structure 260 to transport liquid working fluid 246 fromthe condenser section 248 to the evaporator section 250 by capillaryflow. In some embodiments, the heat pipe 242 may be constructed andarranged such that the liquid working fluid 246 returns to theevaporator section 250 by gravity flow, including solely by gravityflow. For example, heat pipe 242 may be arranged with the condensersection 248 positioned above the evaporator section 250 along thevertical direction V such that condensed working fluid 246 in a liquidstate may flow from the condenser section 248 to the evaporator section250 by gravity. In such embodiments, where the liquid working fluid 246may return to the evaporator section 250 by gravity, wick structure 260may be omitted whereby the liquid working fluid 246 may return to theevaporator section 250 solely by gravity flow.

Notably, certain positions, orientations, and configurations of heatpipe assembly 240 may provide increased rates of thermal transfer fromdrive motor 204 to the flow of wash fluid 206. Several exemplaryconfigurations are illustrated in the figures and described below forthe purpose of explaining aspects of the present subject matter.However, it should be appreciated that these configurations are onlyexemplary and are not intended to limit the subject matter of thepresent application in any manner.

For example, evaporator section 250 of heat pipe 242 may be positionedin direct contact with windings 226 and/or lamination core 228 of drivemotor 204. In this manner, heat pipes 242 may extract thermal energyfrom one of the hottest regions within pump assembly 144. In addition,heat pipe 242 may be molded directly into pump housing 200 and/or motorhousing. In addition, according to exemplary embodiments, evaporatorsection 250 may extend vertically along drive motor 204, may wrap aroundthe drive motor 204, and may be split into multiple capillary pipes ortubes for facilitating improved and even heat transfer from drive motor204 to working fluid 246.

In addition, condenser section 248 of heat pipe 242 may be positionedwithin pump housing 200 at any suitable location placing working fluid246 in thermal communication with the flow of wash fluid 206. Forexample, condenser section 248 may terminate within volute 210.Alternatively, condenser section may pass through pump housing 200 andextend along discharge conduit 212. In addition, condenser section 248may be positioned around pump impeller 202 or may be positioned betweenpump impeller 202 and drive motor 204. In this regard, condenser section248 of heat pipe 242 may include a loop of pipe 270 that extends aroundpump housing 200 within volute 210. For example, loop of pipe 270 mayextend in a radial plane defined by a radial direction R perpendicularto the vertical direction V. In this manner, the surface area of heatpipe 242 in thermal communication with the flow of wash fluid 206 withinpump housing 200 may be maximized thereby increasing the rate of thermaltransfer from the working fluid 246, through heat pipe 242, and into theflow of wash fluid 206.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A washing machine appliance comprising: a sumpfor collecting wash fluid; a pump assembly in fluid communication withthe sump for selectively urging a flow of wash fluid from the sump; anda heat pipe assembly providing thermal communication between the pumpassembly and the flow of wash fluid for transferring thermal energy fromthe pump assembly to the flow of wash fluid.
 2. The washing machineappliance of claim 1, wherein the heat pipe assembly comprises: anevaporator section positioned at one end of the heat pipe assembly; anda condenser section positioned at an opposite end of the heat pipeassembly.
 3. The washing machine appliance of claim 1, wherein the heatpipe assembly comprises a plurality of heat pipes.
 4. The washingmachine appliance of claim 1, wherein the pump assembly comprises: apump housing; a pump impeller rotatably mounted within the pump housing;and a drive motor for selectively rotating the pump impeller to urge theflow of wash fluid within the pump housing.
 5. The washing machineappliance of claim 4, wherein the heat pipe is molded into the pumphousing.
 6. The washing machine appliance of claim 4, wherein the drivemotor is positioned below the pump housing along a vertical direction.7. The washing machine appliance of claim 4, wherein the evaporatorsection of the heat pipe assembly is positioned in direct contact with awinding of the drive motor.
 8. The washing machine appliance of claim 4,wherein the evaporator section of the heat pipe assembly is positionedin direct contact with a lamination core of the drive motor.
 9. Thewashing machine appliance of claim 4, wherein the condenser section ofthe heat pipe assembly is positioned within the pump housing.
 10. Thewashing machine appliance of claim 4, wherein the condenser section ofthe heat pipe assembly is positioned in a discharge conduit.
 11. Thewashing machine appliance of claim 4, wherein the condenser section ofthe heat pipe assembly is positioned around the pump impeller.
 12. Thewashing machine appliance of claim 4, wherein the condenser section ofthe heat pipe assembly is positioned between the pump impeller and thedrive motor.
 13. The washing machine appliance of claim 4, wherein thecondenser section of the heat pipe assembly comprises a loop of pipethat extends around the pump housing within a radial plane.
 14. Awashing machine appliance comprising: a sump for collecting wash fluid;a pump housing in fluid communication with the sump; a pump impellerrotatably mounted within the pump housing; a drive motor for selectivelyrotating the pump impeller to urge a flow of wash fluid within the pumphousing; and a heat pipe assembly comprising an evaporator section and acondenser section, the heat pipe assembly providing thermalcommunication between the drive motor and the flow of wash fluid. 15.The washing machine appliance of claim 14, wherein the evaporatorsection is positioned in direct contact with a winding or a laminationcore of the drive motor.
 16. The washing machine appliance of claim 14,wherein the condenser section is positioned within the pump housing. 17.The washing machine appliance of claim 14, wherein the condenser sectionis positioned in a discharge conduit.
 18. The washing machine applianceof claim 14, wherein the condenser section is positioned around the pumpimpeller.
 19. The washing machine appliance of claim 14, wherein thecondenser section comprises a loop of pipe that extends around the pumphousing within a radial plane.